In pending application Ser. No. 308,586, filed Oct. 5, 1981, there is disclosed and described a filter system wherein the fluid to be filtered is delivered into a receptacle containing a bed of discrete, loosely-associated bodies at a pressure to cause weltering of the bodies within the receptacle, with the result that the solid matter in the fluid is separated from the fluid and settles to the bottom. The separation is brought about by deposit of the solids on the surface of the discrete bodies while quiescent and the rubbing of the deposited solids from the bodies while the latter are in motion, that is, weltering, the weltering being caused by the delivery of the fluid at a substantial pressure into the bed of discrete bodies. The system as disclosed is successful when employed for intermittent filtering operations, for example, filtering the flushing from toilets as contrasted to continuous filtering of, for example, industrial waste because of the fact that during the intervals between flushing operations, the discrete bodies in their quiescent state merge to form an effective screen which intercepts and collects the solids and, during flushing, the weltering produced by the pressure of the fluid entering the bed causes rubbing of the deposited solids from the surfaces and opening up the spaces between the discrete bodies so that the solids, when detached, settle.
The system therein shown is not satisfactory for continuous filtering since continuous flow into the bed will keep the bed for the most part in a continuous state of weltering. Very little of the bed is sufficiently quiescent to act as a filter because of the continuous entrance of fluid. It is the purpose of this invention to provide a filter system embodying the principle of alternately weltering a body of discrete buoyant particles and bringing it to a state of rest to provide an effective filter for filtering solids from industrial fluids where such filtering is expected to be on a continuous basis.